The Technique of FURNITURE MAKING

Common furniture beetle (Anobium punctatum) (21:A)

Commonly known as woodworm, this is the most serious pest, and commonly occurs in roof rafters, floors or general woodwork, including furniture. A few flight holes on the surface of polished timber may not appear serious, but the wood below may be so tunnelled as to reach the point of total collapse, therefore a constant watch should be kept on every item of woodwork.

The mature beetle is oblong shaped, from 1/10 to 1/5 in long (2.5 to 5 mm) and dusty dark brown in colour, with wing-cases covered with lines of small punctures (hence the specific name). It commonly breeds in the dead branches of living trees, fencing-posts, etc., to enter the house by any open window during the dry summer season. After the female beetle has mated about 20 eggs are laid in any suitable crack or crevice, and in particular the exit or flight holes of previous larvae, and the curved white grub, which is equipped with strong biting jaws, hatches in about six weeks to commence its tunnelling by consuming the wood and excreting small pellets of granular dust. When it has reached maturity, which can be anything from one to two years according to the starch content of the wood, the grub, which is now about 1/4 in (6.3 mm) long, moves to close under the surface, where it pupates and tunnels its way upwards to emerge finally as an adult beetle at any time from late May to August. It can then fly off to mate and renew the cycle.

While the sapwood of any wood is particularly liable to infestation (and it is for this reason that in some countries sapwood should never be used in furniture), the heartwoods of certain sweet woods, notably birch, beech, alder and some soft walnuts, are also attacked, while any wood affected by dampness or incipient decay is also prone. Alder, in particular, speedily becomes riddled with furniture beetle, hence the wiseacre's claim that it is better to have a plank or two of alder lying about the timber - or lumber-yard to attract any migrant beetles—a highly invidious contention, for the alder then becomes a first-class breeding-ground. Polished and painted surfaces do, of course, accord protection against the egg - laying female beetle, but invariably there is some hidden crack or crevice or an old flight hole which invites attack, therefore carcass backs and the underframing of furniture should be periodically examined for freshly expelled fine dust. Birch or alder plywoods glued with animal or vegetable glues are particularly susceptible, but resin-glued ply is normally resistant.